https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59769
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:a219139e986a4200a9105d7c1fa63735d2945994 commit r12-5878-ga219139e986a4200a9105d7c1fa63735d2945994 Author: Jonathan Wakely <jwak...@redhat.com> Date: Wed Dec 8 20:58:11 2021 +0000 libstdc++: Implement std::ios_base::noreplace for C++23 [PR59769] This implements my P2467R0 proposal to support opening an fstream in exclusive mode. The new constant is also supported pre-C++23 as std::ios_base::__noreplace. This proposal hasn't been approved for C++23 yet, but I am confident it will be, as this is restoring a feture found in pre-ISO C++ iostreams implementations (and still present in the MSVC library as _Noreplace). If the proposal fails for C++23 we can remove the ios::noreplace name and just keep ios::__noreplace as an extension. libstdc++-v3/ChangeLog: PR libstdc++/59769 * config/io/basic_file_stdio.cc (fopen_mode): Add support for exclusive mode. * include/bits/ios_base.h (_S_noreplace): Define new enumerator. (ios_base::__noreplace): Define. (ios_base::noreplace): Define for C++23. * include/std/version (__cpp_lib_ios_noreplace): Define. * testsuite/27_io/basic_ofstream/open/char/noreplace.cc: New test. * testsuite/27_io/basic_ofstream/open/wchar_t/noreplace.cc: New test.
